1. Field of the Invention
The present invention relates to a vehicle drive assist system.
2. Description of Related Art
Lately, a vehicle drive assist system, which uses a head-up display, has been proposed (see Japanese Unexamined Patent Publication No. 2005-78414). The head-up display projects drive assist information over a vehicle front glass (a windshield) as image information in such a manner that the image information is displayed as a virtual image, which is overlapped with the vehicle front view. With such a vehicle drive assist system, an amount of movement of a sight line (also referred to as a line of sight) of the driver is advantageously reduced, and thereby driver's misinterpretation of the drive assist information can be advantageously reduced. Because of the above reason, the above drive assist system is widely accepted.
At the time of driving the vehicle under some unfavorable environmental conditions, such as driving of the vehicle during rain at night or driving of the vehicle along a snow-covered road, it is sometimes difficult or impossible for a vehicle driver to visually recognize lane markers (white lines or yellow lines), which indicate a traveling lane of the driver's own vehicle. This condition is not desirable for safety reason.
To counteract with the above situation, it is conceivable to use the above drive assist system to display lane guides, which indicate the traveling lane of the own vehicle, over the view seen through the vehicle front glass (i.e., the front view of the vehicle driver) in such a manner that the lane guides are displayed in association with the actual traveling lane. However, under the above unfavorable environmental conditions, the color of the lane guides displayed on the front glass by the head-up display could become similar to its background color and thereby difficult to be recognized by the driver.